There has been known a solid oxide fuel cell (SOFC) which acts at a comparatively high temperature wherein an anode gas is supplied to one side and a cathode gas (air, etc.) is supplied to the other side. The anode electrode used in this SOFC is prone to be readily oxidized when the fuel cell system is stopped and the temperature thereof falls.
Accordingly, for example, in JP2009-295380A, a technology is disclosed to prevent oxidation of the anode electrode by continuing the supply of the anode gas during the fuel cell system is stopped.